The present invention relates generally to air conditioning and heat pump systems and more particularly, but not by way of limitation, relates to refrigerant coils used therein.
The typical indoor coil utilized with heating and cooling indoor equipment is conventionally of an inverted "V" configuration defined by two multi-row, multi-circuit fin/tube refrigerant coil slabs across which air to be cooled is flowed on its way to the conditioned space served by a furnace or air handler. Indoor coils of this type (commonly referred to as "A"-coils in the air conditioning industry) are offered in various nominal tonnages, one air conditioning "ton" being equal to an air cooling capacity of 12,000 BTU/HR. Furnaces and other air handling equipment using this type of coil are normally offered to the residential or commercial customer in an appropriate range of air conditioning tonnages which are established by the size of the A-coil installed in the furnace, or other type of air handler, in conjunction with the correspondingly sized condenser side of the overall refrigeration circuitry.
A representative air conditioning tonnage range for residential furnace applications is, for example, one to five tons, while a representative light commercial tonnage range would be from five to twenty tons. Within this overall cooling capacity range, the tonnage increment between successively larger capacity A-coils is typically 1/2, 1, 21/2 or 5 tons, with the tonnage increments usually being smaller at the lower end of the capacity spectrum.
Conventional refrigerant "A" coils have been the norm in this general furnace and air handler tonnage range for many years and have been, generally speaking, well suited for their intended purpose. However, they are also subject to a variety of well-known problems, limitations and disadvantages, particularly as pertains to their manufacture and incorporation in their associated furnaces, air handlers or the like.
For example, for each A-coil within a given multi-tonnage set thereof, it has heretofore been necessary to manufacture and inventory a differently sized pair of refrigerant coil slabs. As an example, if a manufacturer produces a line of heating and air conditioning equipment having a cooling range of from 11/2 to 20 tons, there may representatively be twelve different capacity A-coils needed-e.g., A-coils of 11/2, 2, 21/2, 3, 31/2, 4, 5, 71/2, 10, 121/2, 15 and 20 ton nominal air cooling capacities. Accordingly, twelve differently sized refrigerant coil slabs must be manufactured and inventoried.
This conventional necessity increases both tooling costs and manufacturing floor space requirements, thereby also increasing the overall manufacturing costs associated with the air conditioning systems into which the A-coils are incorporated. Additionally, each of the A-coils in a necessary capacity range thereof will typically have different depths in the direction of intended air flow therethrough. For example, in up-flow furnaces, progressively larger capacity A-coils will have correspondingly increasing vertical installation height requirements. This can result in the necessity of oversizing the cabinet height of an air handler to accommodate A-coils of varying heights. Moreover, in an attempt to reduce the number of differently dimensioned refrigerant coil slabs which must be manufactured and inventoried to assemble A-coils of the necessary different refrigeration capacities, many manufacturers provide relatively large capacity increments at the upper end of their capacity range. For example, in light commercial air conditioning equipment, the highest capacity unit may be 20 tons, while the next smaller unit may be 15 tons. If the system designer determines that, for the conditioned spaced to be served by the equipment, an air conditioning capacity of 16 tons is needed, he normally must select the 20 ton unit. This undesirably results in a 25% oversizing of the air conditioning system.
In view of the foregoing, it can be seen that it would be desirable to provide a refrigerant coil structure, and manufacturing methods associated therewith, which eliminate or at least substantially reduce the above-mentioned and other problems, limitations and disadvantages heretofore associated with conventional "A-coils" used as the indoor coils of air conditioning and heat pump systems.